The present invention relates to apparatus for manufacturing textiles on a textile loom and in particular to a double dent reed which spaces the individual warp ends on the loom and holds them parallel as the reed pushes the filling yarn into place at the fell of the fabric.
As each pick of the filling yarn is inserted through the shed of the warp yarns, the reed pushes the filling yarn against the already woven part of the fabric in an action commonly referred to as beat-up. Many types of cloth such as very fine fabrics, require a large number of warp yarn ends per inch of reed. It is difficult, if not impossible, to arrange the dents to provide a passage space for each warp end. A problem occurs because the warp yarns forming a shed for insertion of the filling yarn to pass, often stick or cling together due to their close proximity to one another. Maintaining the warp ends parallel becomes difficult during shedding and beating-up. This sticking can also result in breakages when the reed moves forward over the warp yarn ends during beat-up. Slubs, knots, and other imperfections in the individual warp yarn ends also tend to catch on the dents due to the narrow spacing therebetween which causes breakage of the warp yarn ends. Warp breaks result in time consuming loom stops or fabric imperfections, both of which are costly in terms of time and production.
The double dent reed arose in an attempt to more evenly space the warp yarn ends and hold them parallel as the reed beats up each pick of the filling yarn. By the use of two rows of dents, the front row beats the filling yarn against the woven fabric and the dents in the back row of dents are arranged to more evenly space the warp ends. Since there are more dents to hold the yarns parallel without a corresponding decrease in spacing distance, the warp ends pass more freely through the reed. In this manner, ends are spaced more evenly without constriction of the passage spaces between dents. Typical of earlier double dent reed constructions are those shown in U.S. Pat. No. 1,146,478, Dutch Pat. No. 2,823,222, and British Pat. No. 8,525.
As shown in U.S. Pat. No. 4,481,980, which is hereby incorporated herein by this reference, a double dent reed typically includes a frame which carries two rows of dents between a plurality of upper support bars and a plurality of lower support bars. Channels, as in double dent reeds available from Sulzer of Switzerland, may be used in place of the support bars in constructing the frame that carries the two rows of dents.
In a double dent reed, each row of dents includes a plurality of wire dents which are spaced apart side by side along the length of the frame. As schematically shown in FIG. 6, the front row R1 of dents d1 is spaced staggered from the gaps G1 between the dents d2 in the back row R2 of dents d2. In a double dent reed available from Sulzer of Switzerland schematically shown in FIG. 6, there is a 1.7 mm open separation space S between the two rows R1, R2 of dents. The warp yarn ends 12 on the loom are guided through the gaps G1, G2 between the dents d1, d2. One side of the frame is clamped to a moving beam, commonly called a slay, on the loom. The slay moves the reed back and forth to produce the beat-up action. The inertial forces on the upper free side of the reed frame are considerable when utilized on high speed loom operations. One side of the reed is commonly referred to as the beat-up side as it faces the fell of the cloth being woven. The wire dents are normally fairly rigid so that they may beat up the filling yarn against the fabric already woven.
While double dent reeds are an improvement, it has been found that considerable resistance to the passing of the warp ends may still be had in the back row of dents due in part to their staggered positioning relative to the gaps between the dents in the front row. This staggered positioning of the dents in the back row, requires the warp yarns to assume a somewhat tortuous path through the reed. This is particularly a problem in the weaving of terry cloth because of the need to keep the pile ends loose so that the loops found in the terry cloth can be properly formed. The pile ends can be caught on the adjacent ground ends, which are under tension, resulting in pulls and other imperfections in the weave of the terry cloth. Moreover, the tortuous path of the yarn ends between the front and back rows of dents is itself a cause of abrasion of the yarn ends and also results in yarn breaks and the accumulation of lint and size between the rows of dents.